Japanese Patent Application Publication No. 2007-236023 (Patent Document 1) describes a power supply system for a house. The power supply system supplies electrical loads in the house with electric power from a hybrid vehicle. In this power supply system, when the remaining amount of charge of a battery included in the hybrid vehicle is large, electric power stored in the battery is supplied to the house side. On the other hand, when the remaining amount of charge of the battery is small, electric power generated by the driving force of the engine is supplied to the house side (see Patent Document 1).